Its hard to believe that my big tubby boat could tip over easily. The only two variables in determining capsize values are displacement and beam. I would think that keel size, shape, and ballast would be factors also.
I read that if a wave approaches the size of your beam, then you may be toppled. But I think that frequency and shape of waves matter too. In canoe hulls they talk about primary and secondary stability. My Bayfield is 29' with 10'2" beam; most likely regarded as more primary stability, according to the calculators. Other boats in her class, like the Cape Dory and Southern Cross, have less beam and rate as more stable in the capsize value chart.